Hi everyone, I have 1989 MR2 in which the engine shuts off all of a sudden after 20 minutes when the engine warms up. The temperature gauge remains normal halfway between cold and hot the entire time. I have searched the internet and tried all possible suggestions in which I replaced the water pump, thermostat, coolant temperature sensors, flushed all coolant and bleed all the air out of the coolant but still it didn't solve the problem. I have no problem starting the engine at all when it's cold. However, the engine cooling fan never comes on, but if I unplug it from sensor then it comes on right away and never stop unless the engine is shut off. As soon as I plugged the fan back on to the sensor, the fan stops working. Now, I'm stumped. I heard someone mention something about the main relay. Could that be the cause? Can anyone help me please.
the engine cooling fan never comes on, but if I unplug it from sensor then it comes on right away and never stop unless the engine is shut off. As soon as I plugged the fan back on to the sensor, the fan stops working. .
Thats normal.The same is true for the 2nd gens.
The fan WILL come on when you disconnect it from the sensor. When it's plugged in, the fan will only come on when the sensor reads a certain engine bay temperature. While plugged in, you will probably never see the fan running. I leave mine disconnected all the time to help prevent heat soak.
MR2Jedi, thanks for your reply. I guess the fan issue is normal and doesn't relate to the engine shutdown issue then. However, any idea why the engine would shut off when it warmed up? At first, I thought it was overheating, but I had replaced all that I can think of that would cause the overheating and all failed to resolve the issue. What other things might have cause the engine to shutdown when hot? Has anyone ran into this issue or advice please. I've been struggling with this issue for a long time and spent a lot of money and time into it already but could not determine the cause. I'd like to get this car back on the road again instead of let it rust out inside my garage. Thanks in advance.
Does the 1st gen have a coolant temp sensor for the ECU? ( not temp sending unit for gauge).
If so, if it's malfunctioning, instead of idling down after reaching temp, it may be shutting it down via ECU.
I don't know if it's the same one you are talking about but I already replaced two coolant temperature sensors and that didn't resolve the issue. Not sure how many there would be all together. My friend said he once had an Acura Legend that had similar problem to mine, and what he did was replaced the Main Relay. However, there are different relays. How can I tell which is the main relay or which to look for as the suspect for this issue? Suggestions please. Anyone?
Where do I find the "MKI How To"? Is it in the manual that came with the car?
BTW, I started the car again last evening and let it runs until the engine die. Then I reached out and feel the two coolant pipes underneath the car and both were cold. I also feel the two hoses in and out of the radiator and both were cold as well. But the hoses by the engines are hot and the coolant inside are hot like boiling water. Is this normal?
I thought the thermostat was stuck too, but I had already removed the thermostat and tested it in boiling water and the spring did compressed and open up the valve. So that means it is still working. Besides, the thermostat is new, so it couldn't be stuck in the closed mode. I also thought that may be there is a clog in the coolant pipe, but I flushed the whole system out and doesn't seem to be clogging anywhere. The Radiator is also brand new as well. I then thought the water pump is probably bad and not pumping the coolant, so I replaced it with a brand new one. With all three (water pump, thermostat, and radiator) brand new, I can't understand why it seems like the coolant is not cycling through the entire cooling system. All the hot coolant seems to be stuck at the engine. Any advice will be greatly appreciated.
I think you are barking up the wrong tree. Probably nothing to do with the cooling system. A better bet would be your ignition or fuel system. Some component is failing when it worms up.
You need to see what it’s not doing when it shuts off. First thing is see if there is a good spark at the plugs.
Mr2Jedi, I don't know if there is a cold start injector in the car or not. But what does a cold start injector has to do with the engine shut off when hot? Because the car fire up just fine when it's cold. Only take one try and it fires right up. If there is one, where would it be located?
Unbelieveableny, guess i'm not sure what you mean by clear picture of the engine. If you are referring to knowledge about the parts in the engine then, the answer is NO. I can identify most of the parts, but not all of them. I wouldn't be here asking for help if I know the engine inside out.
GeoffBooth, like I mentioned above. The car fires up just fine with just one click. I have no problem starting the car at all. And once it starts up, it would stay up until the engine is hot then it dies again. I won't be able to start the car again until the engine cools down 5 or 10 minutes later. Does that still sound like a ignition and spark plug problem?
Mr2Jedi, I But what does a cold start injector has to do with the engine shut off when hot?
I refered to cold start injector timer switch, not the injector itself.I was thinking if switch is malfunctioning, it may be sending a screwed up signal to ECU and then engine shutting down when warmed up. Grasping at straws here .
Quote:
GeoffBooth
I think you are barking up the wrong tree. Probably nothing to do with the cooling system. A better bet would be your ignition or fuel system. Some component is failing when it worms up.
You need to see what it’s not doing when it shuts off. First thing is see if there is a good spark at the plugs.
I think he's onto something. Coil , ignitor or fuel pump resistor may stop working after engine warms. Check for spark and fuel after engine dies.
I had the exact same problem several years ago and it was the igniter. There are tests you could do with a volt meter but. They can be got for around $25 from a junk yard. You are probably getting a check engine light when it shuts off. Have you checked the codes?
Thanks for all the great suggestions. I've been busy lately so haven't had time to work on it yet. I will tackle those suggestions as soon as I find some free time. BTW, there is no code or check engine light when the engine stopped. The engine just shut off and all lights in the dash board are on just as when you turn the key to on without starting the car.
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Please help, 1989 MR2 Engine shut off when hot
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